Means of testing insulated wires.



i-No; 856,012. PATENTED JUNE 4, 1907..

f N. A. WOLGOTT. y

MEANS OF TESTING INSULATED WIRES.

APPLIOATION FILED MAY 5, 1906.

MM 7 v v j UNITED STATEATENT OFFICE.

NEWTON A. WOLOOTT, OF WARREN, OHIO, ASSIGNOR TO THE PACKARD ELECTRIC COMPANY, OF WARREN, OHIO, A CORPORATION OF OHIO.

MEANS OF TESTING INSULATED WIRES- Specification of Letters Patent.

Patented June 4, 1907- Application filed May 5, 1906. Serial No- 315,359.

To all whom it may'concern:

Be it known that I, NEWTON A. WOLCOTT,

of Warren, in the county of Trumbull and State of Ohio, have invented certain new and useful Improvements in Means for Test-- mg Insulated Wires; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it a pertains to make and use the same.

he object of this invention is to rovide means for detecting im erfections in tiie insulation of wires or ca les without actually energizing the core save where there is imperfect insulation.

A further object is to provide means of the character stated for testing cables as they are being manufactured, that is to say, adevice which will be continuously in operation as the cables come from the machines, or at any other stage of forming the insulation.

The invention will be hereinafter fully set forth and particularly pointed out in the claims. I

In the accom anying drawings, Figure 1 is an elevation of the means for carrying out my invention where continuous service is required. Figs. 2, 3 and 4 show modified forms. j

Referring to the drawings, 1' designates a base upon which are mounted two metallic dielectric contacts 2 and 3, preferably in the form of spring sleeves or cylinders having central openings for the passa e of the insulated wire or cable 4, with whic the contacts have a constant brushing engagement. These contacts are mounted in supports 5 and are in axial line with each other and with a guide 6.

7 designates a transformer, the terminals of the secondary wiring 8 of which are secured to posts 9 on the supports 5, thus electrically connecting the secondary with the contacts 2 and 3.

The primary 10 is connected through a switch 12 to a generator 13, or other source of electrical supply. lVithin the primary circuit I locate an automatic cut out 14 for effecting the actuation of a hell or other alarm 15, which cut out will be automatically operated instantly the secondary circuit is closed, since the closing thereof varies the current in the primary circuit, and this variation results in the operation of the automatic 'cut out.- This may or may not cut out the the contact with transformer. The cut out is conventionally shown as embodyin a solenoid coil 16 and an armature 17 1n t e form of a bell crank lever which normally holds a switch 18 and closes the circuit through the solenoid. The attraction of the armature by the solenoid will effect the automatic disengagement or release of the switch 18 and the closing of the bell circuit, and, according to the form shown in Fig. 1, the opening of the primary circuit, the solenold wiring being broken.

The arran ement described is especially applicable w ere continuous service is reulred, as in testingcables as they come from t e machine. Any marked weakening of the dielectric strength will reduce the resistance in the secondary circuit, and this in turn will effect the automatic release of switch 18, thereby giving an alarm when a poorly insulated spot is passing either of the contacts. In other words, the secondary voltage of the transformer is somewhat less than the puncture voltage of the two dielectrlcs 1n serles, and hence the alarm is given when there is a failure on one side, or even a marked variation in the dielectric strength. This will indicate a weakness in the cable although perhaps not sul'licient to break down the dielectrics.

It is manifest that the idea dominating the present invention may be carried out in various ways, and with other means than that described. ln Fig. 2 I have shown the primary wiring in constant closed relation to the solenoidcut out, so that the release of the switch will merely cause the actuation of the alarm.

l Vhere the tester is not employed continuously, or Where a particular form of test is desired, I may substitute an induction coil 20 for the transformer, (see Fig. 3) in which event the secondary winding has connected thereto adjustable sparkers 21, and within the primary winding, which has a switch connection to a battery 22, is a make and break contact device 23. quired to continuously jump the spark gap is more than suflicient to break down the insulation between the exterior of the cable and the-core thereof, but not sullicient to break down two such points of insulation in series. Hence the tester, thus adj us ted, will not break down the cable insulation, with the two di- The voltage re- Lil point of insulation engages one of the brushing contacts, say 3, the puncture voltage of the two dielectrics in series is sufficiently lessened to permit a ready transfer of energy from the contact 3 to the core center. will leave but a single dielectric between the other contact, 2, and the common core, the

potential being more than suflicient to break through this insulation. Thus is established a complete secondary circuit, and vigorous sparking will occur at the contacts instead of at the sparkers. According to the means last described the attendant becomes aware of the defect in the insulation by the cessa 'tion of the sparks at the spark gap, and the vigorous sparking at the .cable contacts. The sound of the sparking at such contacts is quite different from that at the sparkers, and this in itself affords means for indicating or detecting the defect if the operator does not happen to be looking the instant the sparking occurs at the contacts.

In Fig. 4 I have shown a source of poten.

tial 24 applied direct to the contacts without the interposition of any transforming device,

and circuit breaker 25 may or may not be included in the circuit. If included, it may be used as indicated in either Figs. 1 or 2..

I claim as my invention:

1. In an insulated cable tester, two dielectric contacts with which the cable engages, and means for supplying to such contacts a current, of a potential less than the voltage of the two dielectrics in series but sufiicient to energize one contact when the other contact energizes the core of the cable.

2. In an insulated cable tester, two dielectric contacts with which the cable engages, a source of electrical supply, and primary and secondary windings, the former being connected to a source of supply, and the latter to the contacts for supplying thereto a voltage less than the puncture voltage of the two dielectrics in series.

4. In an insulated cable tester, two dielectric contacts with which the cable engages, a source-of electrical supply, primary and secondary windings, the latter being connected to said contacts and the former to the source of supply, and means for cutting outthe pri- This ma'ry when there is a marked variation or failure in the dielectric strength of the secondarIy. v l 5. n an insulated cabletester, two dlelectric contacts with which the cable" engages, a source of electrical supply, primary and secondary windings, the'latter being connected to said contacts and the for mer to the source of supply, an alarm connected to" the primary winding, and means for causing such alarm to be actuated and cut out the pri mary when there isa marked variation or failure in the dielectric strength'of the secondary.

6. In an insulated cable tester, two dielectric contacts with which the cable engages, a source of electrical supply, and a transformer or induction coil, the secondary winding of which is connected to'said contacts, the potential being less than the voltage of the two contacts in series, but sufficient to close the secondary circuit when either contact energizes the core of the cable through a point of insufficient insulation.

7. An insulated. cable tester having two dielectric contacts, and means for supplying an electric current to said contacts of such potentiality that the contacts in series are quiescent, either being thrown in circuit with the other through the core of a cable when an insufficiently insulated portion thereof engages such other contact. I

8. The herein-described tester for insulated cables, comprising two contacts with which the cables have a wiping contact, a 5 transformer, having its secondary winding connected to said contacts, and a source of electrical supply connected to the primary winding of such transformer, the secondary circuit being closed through the cable core 100 and. either of the contactswhen the other contact is engaged bya defective section of insulation.

9. The herein-described tester for insulated cables, comprising a base, two contacts 10 5 having openings for a cable, terminal posts 'mounted on said contacts, a transformer,

specification in the presence of two subscrib- 1 1 5 ing Witnesses.

NEWTON A. woLcoTT. Witnesses CHAS. P. NYE, G. M. BATES 

